With just 12 days of pre-season testing available, today's wet weather will have hampered preparations for Melbourne all along the pitlane. What's more, there's only five days to regroup before the third and final test.

As useful as getting some experience on wet weather tyres can be, the risk of damaging unique parts is too great to commit to a lot of running. Yet despite the weather some technical updates have appeared on track, with smaller parts being tested on a number of cars.

Marussia has fitted a different engine cover to the MR02. The car launched with an unusual arched and rounded engine cover, but this has now been switched for a more conventional, shrunken cover with the shark fin to meet the minimum legal dimensions. It's not clear if this is the preferred race set-up or whether the launch format bodywork will return.

Marussia's car remains one of the simpler designs in the pitlane. The team's windtunnel programme constitutes something like one quarter of the tunnel time others enjoy. With this limitation it's not surprising that the more intricate parts will take time to come through to the race car.

Lotus

During a spell of drier weather Lotus fitted the car with the new hard tyres and ran some special sensors on the axle, designed to measure the forces experienced at the wheel. They are produced by a company called Kistler.

These wheel-force sensors are commonly used in the automotive industry and in Lotus's case are used to gather data to build up an accurate model of the new hard tyre. Having an accurate tyre model will aid Lotus in setting up simulations to predict performance and suspension set-ups for the hard tyre.

Under the technical regulations, mirrors can enjoy a generous amount of plan area which the teams can exploit. Thus the new set-up on the Toro Rosso sports a small horizontal fin, to which the mirror pod is mounted. The fin will act to create a vortex running down the sidepod tops to the exhaust outlet, adding to the bending effect the airflow has on the exhaust plume.

The team also ran with a large aero rake to measure the airflow ahead of the floor and the sidepods' undercut. As the rig is a multi-purpose set-up not all of the section being used is fitted with the Kiel probes.

Ferrari

A brief run was completed with a strake running across the side of the nose cone. The strake arched up from the nose tip to where the top wishbone meets the nose.

This test was conducted with flow visualisation paint applied to the flanks of the nose. Flow visualisation is an oil based paint that has fluorescent particles suspended in it. As it's non-drying, the paint forms streaks across the bodywork. This shows the surface flows along the bodywork, and the resulting streaks will be compared to CFD or windtunnel results.

Teams will want to see where the streaks in the flow visualisation go, to make sure they follow the same direction as predicted. They also want the flow to remain attached to the bodywork, so continuous streaks of paint should be evident.

Several teams use nose strakes; Force India, for example, uses them in order to meet the regulations on nose cross-section. Instead, Ferrari appears to be using the strake to manage airflow over the front suspension. Subsequent runs were completed without the strake, so it will be interesting to see if it returns.

Williams

Continuing to test with different combinations of nose and front wing, the team spared some time for pitstop practice. This was the first chance to see the new blown front axles. As previously explained, Williams ducts air through the front axle for a beneficial aerodynamic effect on the front tyres' wake.

To do this legally, the duct passing inside the front axle must end flush with the wheelnut. This makes the axles shorter and blunter than other teams who have more rounded or pointed designs.

This has the problem that wheel changes at pitstops may be less accurate, as the wheel and nut assembly need to be centred on the axles quickly and precisely. The rounded axles of its rivals help the mechanics align things quickly. It is possible that Williams has shaped the inside face of the front wheel to achieve a similar aligning effect.

Any benefit in lap time from the blown front axle may be lost with slower pitstops, so it's critical Williams gets the design right in this area.

Save it for a rainy day

If a team can't run the car on track due to the weather, then having the complete race team in attendance is a good opportunity to prepare for pitstops. Most of the pitstop equipment will be brought to tests: the air hose rig, the traffic light system, the jacks and, of course, wheel guns.

Some teams have painted the pitlane with markings to denote how accurately the car stops. These markings are accurate to five centimetres and show the team how close the driver gets to stopping the car in the pit box, both lengthwise and across. Some teams such as Red Bull even have laser sensors to measure the accuracy.

The same rig that passes the air hoses safely over the pit box also houses the traffic light system, laser sensors and other unexpected systems.

Most teams will record the pitstop from above with a number of small rugged cameras so they can replay the pitstop for training purposes, to work out where time was lost.

The driver still has a job to do by stopping accurately, but the main aim of pitstop practice is to drill the pit crew. Already back at the factory the pit crew will be under a personal trainer. They will also have completed countless practice stops on a spare chassis. This will be an old chassis and will have battered-looking hubs and wheel nuts from the repeated practice.

At tests teams will mainly do static pitstop practice, which is when the car is pushed into position and not driven under its own power. For this the team often fits spare wheels with wet tyres and old nose cones, to prevent damaging race-ready parts. Aside from aiming for that elusive two-second tyre change, teams will also practice changing nose cones, adjusting the front wing and other maintenance completed at pitstops.

TECH BLOG DAY 3: FERRARI'S REAR-END DILEMMA

Three days into the second test and, while the hard work continues for the teams, no new parts have yet been evident. In their absence, the diligent method of testing old and new parts back-to-back has formed the bulk of the teams' respective programmes.

The importance of exhausts

One area that teams have been focusing on, and where developments can be expected before Barcelona, is the exhausts. Developing a new exhaust system to suit the car's aerodynamics is a complex process, particularly as aero gains often come at the loss of engine power.

AUTOSPORT spoke to Luca Marmorini, head of Ferrari's engine department, at Barcelona. Talk inevitably touched upon exhaust legality in the wake of the FIA's comments on the Williams and Caterham solutions and while Ferrari insist it will not follow a similar path, the team's current exhaust package is far from definitive.

"It is very interesting. We are working on a different solution as well," Marmorini said. "It's contributing to the last few tenths.

"We are testing on the dyno and in the windtunnel. At the moment all engine people are a little bit unhappy that we have to compromise engine performance.

"There is a lot of work from engine people to recover some performance. We have worked on this, our customer teams have worked on this; everyone is working the same to reduce the impact of the exhaust. But we can afford to lose some horsepower if the car is quicker."

The hard work is not just to regain the power loss; it's also critical to ensure the physical exhaust pipework is reliable. Being one of the few parts on the car fabricated by hand - from welded sections of Inconel metal - it's difficult to ensure the system can withstand the heat and vibration.

As Marmorini details, "an exhaust failing can force you to stop the car, so it's as critical as a piston or a gearbox failing. We therefore have a lot of concern about introducing the latest exhaust solution without the correct number of tests, but in the end we have to push.

"We have a process to test some different exhausts on the dyno, but the more you push this, the more of a worry the reliability can be."

As much as dyno testing is important, Marmorini says that physical testing on track is also paramount. "On Wednesday morning we tried to test the exhaust to the very end of its life," he explains, "because we definitely need to know what the limit of the exhaust's life is."

Any new exhaust solution will need to be track-tested, to check the effect on the aerodynamics, the engine and reliability. And with the parts unlikely to be run until the final test, there will be just two weeks to assess them until Melbourne.

"I think every engine person is a little bit uncomfortable, but we will be sure that in Melbourne we will have solutions that are tested enough," Marmorini says.

It's likely that in the last few days of testing next week every team will have updated exhausts, sidepods and other parts. It's brinkmanship in F1 at this time of the year: new parts bring performance, but also risks. By the time the chequered flag is out at Barcelona on Sunday afternoon next week, it will be too late for the teams if anything has gone wrong with the new parts.

Ferrari

Today, the Ferrari was set up with an intricate aero rake to test the airflow passing under the diffuser.

As with most test rigs it only measures on one side of the car; the readings are taken along the straight when the airflow is also straight so that no cross-flows can upset the readings.

Many teams are testing cooling outlets, but the relatively low temperatures in Spain at this time of the year are not enough to actually stress the car's cooling system for the conditions we will see at the first flyaway races. However, by opening up the cooling outlets teams can measure the delta between the running temperature of the different openings, which will help calculate the relative cooling benefit of different set-ups.

Williams, with its tiny rear end, creates a truncated engine cover ending directly behind the power unit. For hot races this cover is opened up and the hot air within the sidepods from the engine and radiators can vent out. The more cooling outlets you run, the more drag they create, reducing top speed. Teams will always opt to run bodywork as closed as possible.

Looking at the opening at the back of the engine, the silver inner panels would have been termed heat-shielding in previous years. But now this shielding is as much about the internal aerodynamics of the car as about protecting other parts from the heat.

The route air takes from the radiators to the cooling exit will be streamlined and shaped by these heat shields enclosing the engine and other mechanicals.

Testing at Barcelona gives the photographers a great chance to look down vertically on the cars. This unusual view shows us how the bodywork slims around the engine and gearbox to create the classic 'coke bottle' shape slim rear end.

Rear ends are getting ever slimmer, as cooling outlet areas are shifted to the gearbox to allow the sidepods to merge into the gearbox fairing. This often makes the rear bodywork narrower than the stepped underfloor, allowing more flow to pass over the diffuser.

The attached photo also gives us a view of the bodywork forming the floor around the rear wheels and diffuser. The bodywork ahead of and inside the rear wheel is made from titanium: this is to cope with the heat from the exhausts but it also opens up opportunities to make the parts rapidly by either machining or laser sintering. This latter process is a form of 3D printing that can make aluminium or titanium parts ready to fit direct to the car.

In the case of the Lotus E21, the floor around the tyre does not follow the tyre closely but is spaced wide away. This allows the vortex flow from the exhaust pipes to pass under the floor to help seal the gap between diffuser and floor, maintaining the low pressure under the floor and preventing the lateral flow coming off the rear tyres passing into the diffuser.

Lotus's diffuser is well known for expanding rapidly to exit almost sideways behind the rear tyre. The tail of the diffuser is just visible at the top of the picture, between the tyre and rear wing. This rapid divergence of the diffuser helps lower pressure under the floor, producing even more downforce. No other team has such aggressive lateral expansion of the diffuser.

TECH BLOG DAY 2: SAUBER'S NEW TRICK

After yesterday's technical intrigue surrounding the vanes run by both Williams and Caterham, the second day of running at Barcelona was less controversial.

But Sauber did catch the eye when it introduced something significantly new over and above its eye-catching narrow sidepods.

Following speculation at its launch, Sauber at last unveiled its drag reduction device (DRD), which is design to stall the rear wing at higher speeds on the straights.

In effect, this concept is the passive version of the f-ducts introduced in 2010 as they do not rely on the driver or moving parts to activate them.

Sauber's uses a fluid switch to redirect the airflow from a neutral outlet over the beam wing to the stalling outlet, which points upwards and channels it to the rear wing. The fluid switch is activated purely by the increase in speed and is deactivated once the car's speed drops to a certain point.

When activated, the airflow directed into the stalling outlet is channelled to break up the airflow under the rear wing. This cuts downforce and drag, resulting in a boost in top speed and acceleration. Unlike the DRS, this can be used whenever the car exceeds a certain speed.

As suspected, Sauber's DRD is used in conjunction with the delta-shaped rear wing tested yesterday.

The angled underside of the wing probably helps the stalling effect spreading from the duct blowing under the rear wing.

With DRS use restricted only to the designated activation zones in practice and qualifying, as well as in the race, this is a ripe area for development.

Any team getting this complex system to work will have an advantage at circuits where the lap time is influenced significantly by the trade-off between downforce and top speed.

The Silverstone-based team is running a revised front wing featuring a different cascade arrangement fitted to the main part.

Cascade is the term applied to the winglets and vanes added above the main front wing and in Force India's case, they are fitted to the endplate with an r-shaped vane added inboard of these.

Such cascades often appear to be downforce-producing elements but they are most effective as flow conditioners, which alter the flow structure come off the back of the front wing and around the front tyres.

The Force India winglets are slightly narrow but their twisted profile produces a strong vortex that spirals around the front tyre to improve both the airflow in the tyres' wake and further downstream on the car.

The r-vane has a similar affect on the airflow passing inboard of the front tyre.

The rest of the front wing is similar to the wing tested in Jerez. As cascades are largely a bolt-on item, switching between specifications is relatively simple.

TECH BLOG DAY 1: EXHAUSTING TIMES

Formula 1 testing resumed on Tuesday at Barcelona with the launch of Williams's new FW35 meaning that every one of the 11 teams has now run its 2013 machine.

But despite being just the fifth day of pre-season action, the sport's first technical controversy of the year - that of the exhausts on the Williams and Caterham machines - is already upon us.

Elsewhere, the rest of the teams got on with the business of piling on the laps and running in their latest updates.

With Barcelona a more challenging track than Jerez, the Spanish Grand Prix venue is where teams will really begin to learn their cars. Small updates have already been introduced and through the week these will be tested back-to-back against proven parts.

The aim of these runs is not to find out-and-out lap times, but to generate data, improve reliability and learn more about Pirelli's 2013-spec tyres. Not until next week's final test - also at Barcelona - will teams run through qualifying simulations. That's always worth waiting for.

Both the Williams and Caterham cars were launched with contentious bodywork around their exhausts, and each team adopted outwardly legal ways to use bodywork to help deflect exhaust gases down towards the diffuser. By Tuesday morning, however, it became clear that neither of the designs will be permitted to run during the world championship season, and must be removed in time for the Australian Grand Prix.

Rules to effectively ban exhaust-blown diffusers were brought in last year. Among these rules was a stipulation that was the final 100mm of the exhaust tail pipe must point at least 10-degrees upwards, and a ban on bodywork over an imaginary cone aligned with the exhausts axis.

Teams have wasted no time in trying to gain back the benefit, the use of the Coanda and downwash aerodynamic effects in particular being utilised to bend the exhaust plumes back towards the diffuser edge.

It is these effects that have created room for the kind of thinking employed by Williams and Caterham. By these upwards gases actually flowing downwards, bodywork can theroretically be placed over their path while remaining within the aforementioned imaginary cone.

The Williams exhaust outlet is split into two exits; one upper and one lower. The upper exit marks the are through which the imaginary cone passes while the lower one reflects where the exhaust plume is actually directed. This demonstrates both the extent to which current sidepod design is helping the redirection of the exhaust plume, and the fact that the current technical regulations do not prohibit this.

The Williams team's defence is that the exhaust opening meets the rules by being both a single opening (by joining the two openings with via thin slot) and by not passing over the imaginary cone. However early last year a technical directive (which is not publically available) was issued stating that exhaust gases cannot be manipulated by bodywork over the plume.

The FIA has now enforced this final point, impressing on teams that the channel formed around the exhaust outlet must have an open top with vertical sides in order to prevent bodywork from passing over both the imaginary and the actual exhaust gas path.

Losing these developments will be a small loss for both teams, but not a fundamental one in terms of their on-track performances.

Several novelties were apparent on the C32, with a sensor pod, new rear wing and some inlets, possibly to form part of a drag reduction device. The sensor pod was reminiscent of a Formula 3 car's airbox while a teardrop-shaped pod emerged from the roll hoop and contained an infrared camera to measure either tyre temperatures or - more likely - bodywork temperatures affected by the exhaust.

The new rear wing formed a slight delta shape with the wing forming a flat 'V' shape in front profile. This new shape might be related to the DRD inlet also fitted to the car during testing. Even at the car's launch the removable bodywork panel over the roll hoop suggested some form of DRD would be fitted to the car.

On Tuesday morning the panel was swapped for one with two Lotus-like inlets. It's unlikely these are for cooling purposes and so are probably the start of the ductwork used to stall the rear wing at high speed. As yet the rest of the ductwork does not appear to be fitted, but the angled underside of the new rear wing could help promote the stalling effect across the wing when the stalling-duct is blowing underneath it. A close eye will be kept on developments from the team over the course of the test.

Another team with a DRD in the offing, Lotus actually ran the E21 at Jerez for a brief while with some extra ductwork fitted. On Tuesday the car only sported the two closed inlets flanking the roll hoop. However the roll hoop inlet itself also raises some interest.

Normally the snorkel shape formed by the roll hoop is a simple duct leading into the engines airbox.

On the E21 on Tuesday the inlet appeared to be split with ductwork with two pieces of additional bodywork inside. These could be related to cooling some parts within the engine bay, but it is more likely that they are another part in the DRD jigsaw.

Another innovation missed from the Jerez test is the slot under the nose of the F138. As with Red Bull and Sauber, Ferrari has have fitted a wide opening under the nose near to the point at which it joins the chassis. Unlike the aforementioned teams, this slot feeds directly back into a corresponding gap in the front of the monocoque.

While this will serve as a source of cooling air for the driver, steering rack and electronics inside the footwell, the actual benefit of the slot is on the external aerodynamics.

The slots bleeds air building up under the nose, which improves the airflow further back along the car. Having this also allows the Ferrari to have a much shallower nose and a steeper underside where it meets the chassis. All of this effect reduces the blockage the nose has on airflow passing in-between the front wheels.

It is rare to see parts removed from F1 cars, so this clear shot of the Caterham exhausts is a real bonus. You can see the four primary exhaust pipes joining into one secondary pipe. Each of these pipes is bolted the cylinder with just two fasteners!

At the collector there are two sensors bolted into the pipework, one to measure the exhaust gas temperature (up to 900c) and the other to detect the stoichiometric ratio (the amount of oxygen in the exhaust gases). This information is fed back into the engine-management system to ensure the car is fuelled correctly.

Then the single secondary pipe loops back on itself, and sprouting from this is the Helmholtz chamber, visible on the left of the picture. This resonant chamber helps the exhaust tuning to improve drivability, but also the smoothes the flow of exhaust gasses for aerodynamic purposes. Other engine manufacturers also exploit this chamber, while only the Cosworth engine has yet to be seen with such a set-up.

The actual exhaust outlet is not visible behind the other pipework, but the controversial carbonfibre exhaust duct is. It is this duct, which features a vane inside, that the FIA acted on to effectively ban on Tuesday.

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